The invention relates to a tool holder for a rotary and/or chisel hammer with a sleeve body into the central opening of which the tool bit, with its shaft provided with at least one axially extending locking groove which is closed at both ends, can be inserted from the front and in the wall of which sleeve body at least one axis-parallel through opening is provided, with a cylindrical locking body disposed in the through opening, the axial length of which is smaller than the axial length of the through opening, with an adjustment sleeve surrounding the sleeve body in the area of the through opening which can be moved against spring pressure out of a locking position, in which it prevents a radially outward movement of the locking body, which is located at the front end of the through opening and which protrudes into the central opening, into a release position, in which the locking body located at the front end of the through opening can be displaced radially outwards from the area of the central opening, wherein when the tool bit is inserted the locking body can be moved by it from the position at the front end of the through opening against spring pressure into a rear position in which it is displaced radially outwards out of the area of central opening, as well as with a support for preventing tilting movements of the locking body into blocked positions.
On a known tool holder of this type (GB Patent No 2171340) the through opening in the sleeve body which receives the cylindrical locking body continues radially outwards into an axially extending groove, which diverges outwards and into which a slide block is inserted which has a supporting surface, which, at least with the adjustment sleeve located in the locking position, over the complete axial length of the locking body rests against the outer side of its cylindrical surface and which at the rear end has a stop surface formed by a stop nose provided at the slide block which stop nose extends into the through opening. The area provided with the slide block is surrounded by a control ring which cannot be displaced axially and radially and which has control surfaces on its inner side, of which the first control surface located radially farther in when engaging with the slide block prevents its displacement and thus also the displacement of the locking body radially outwards whilst the second control surface located axially farther to the rear is located radially farther out so that the slide block with axial displacement rearwards from the area of the first control surface can move radially outwards in the area of the second control surface so that the locking body can also be displaced radially outwards and no longer protrudes into the central opening of the sleeve body. With such a position of the locking body a tool bit can be inserted and withdrawn.
The control ring is surrounded by the adjustment sleeve which can be displaced rearwards in relation to the control ring from its front locking position against the pressure of the spring acting on the slide block. With such a displacement movement a stop provided at the adjustment sleeve and extending rearwards effects a displacement of the slide block from the area of the first control surface of the control ring rearwards into the area of the second control surface so that slide block and locking body can be displaced radially outwards. In this way a tool bit located in the tool holder can be removed from the tool holder.
When a tool bit is inserted the rear end of its shaft comes into contact with the part of the front end of the locking body which protrudes inwards into the central opening of the sleeve body and displaces it and, as a result of engagement with the stop surface formed by the stop nose of the slide block with the rear end of the locking body, also displaces the slide block rearwards so that it can move out of the area of the first control surface of the control ring and the slide block and locking body can move radially outwards so that then the end of the shaft of the tool bit can slide along under the locking body which after this as a result of the spring pressure acting on the slide block can enter the locking groove in the shaft of the tool bit and can be moved forwards in the opening of the sleeve body. In this position a radial displacement of the locking body outwards is prevented by the contact of the slide block at the first control surface of the control ring.
The known tool holder is thus suitable for holding rotary and/or chisel type tool bits which are provided in their round shaft with one or more axial locking grooves which are closed at the ends as is the case for example with tool bits of the SDS system. At the same time the locking bodies enable not only a reliable holding of the tool bits in the tool holder while making it possible to have a limited axial backward and forward movement but with the provision of several of this type of locking bodies, these locking bodies can also be used for transmitting the torque for the rotary movement of the tool onto it, although generally axial ribs formed in the tool holder as known from the SDS system, which engage in the grooves of the tool shaft which are open to the rear, are used for this purpose.
As can be seen the known tool holder is composed of a large number of very specially formed individual elements so that not only the sleeve body in addition to the at least one through opening requires a groove continuing radially outwards from this but at least one very specially formed slide block and a control ring provided with various control surfaces are also required to enable the various displacement movements of the cylindrical locking body to be achieved without blocking tilting movements.
A tool holder is also known for a rotary and/or chisel hammer (GB Patent No. 2 096 045) which comprises less individual elements than the known tool holder described above. On this known tool holder which is designed to receive SDS drill bits the sole locking body consists, however, of a ball which in the locking position of the adjustment sleeve is supported against displacement radially outwards and which, when a drill bit is inserted with the displacement of a ring body against spring pressure axially rearwards in the through opening, is moved rearwards so that it can move radially outwards so as to permit the passage of the rear end of the bit shaft. In order to release an inserted drill bit the adjustment sleeve is moved out of its locking position into the release position which is effected by moving the adjustment sleeve rearwards--although this could conceivably be done by a rotational movement--so that the locking body can then be displaced radially outwards and the drill bit can be removed.
The problem of the aligned, unblocked holding of the locking body in various operating positions does not occur on this known tool holder as the locking body is spherical and not cylindrical. A spherical locking body is, however, subject to a good deal of wear as a result of the forces which occur particularly with larger rotary and chisel hammers and is thus unsuitable for this application.